1. Field of the Invention
The present invention relates to photonic switches. More particularly, this invention pertains to a mechanical switch suitable for incorporation into optical switching arrays.
2. Description of the Prior Art
The two primary operational modes of switching signals in an optical network are OEO (optical-electrical-optical) and photonic. They differ in that the switching function is accomplished electronically in the OEO mode while photonic switching is accomplished by the deflection of beams. Such beam deflections may be occasioned by numerous means, the most prominent of which utilizes MEMS (microelectromechanical systems) technology.
In a MEMS system, switching is accomplished by the use of mirrors whose orientations are responsive to control signals. Often a plurality of mirrors is arranged within a switching module architecture having a plurality of input and output ports. Numerous switching modules may, in turn, be grouped or cascaded together to form large switches. Examples of switching architectures include crossbar switches, Benes switches, Spanke-Benes switches and Spanke switches.
The MEMS switches that comprise switching architectures generally comprise pluralities of planar mirrors, each mirror being hinged at its bottom edge to rotate upwardly and downwardly to a preferred attitude to either intercept and redirect an input beam or to permit the beam to bypass its position without effect. The light passes through the switch in a plane that is parallel to the bottom surface of a switch housing. Movements of the mirrors between preferred attitudes are responsive to electromechanical forces.
Switching accuracy is dependent upon the repeatable, precise steering of light beams from input to output ports. Mirrors that are switched to different angular orientations about a hinge are subject to tilt bias due the difficulty of assuring return to precise xe2x80x9cONxe2x80x9d and xe2x80x9cOFFxe2x80x9d positions. This may cause an input light beam to be deflected off-center either losing or dissipating the optical signal and causing a type of insertion loss.
In addition, should a mirror of the array require replacement, an active alignment process is required to assure that the new mirror is properly oriented. This greatly complicates the practical application of switching module architectures comprising numerous hinged mirrors.
The preceding and other shortcomings of the prior art are addressed by the present invention that provides, in a first aspect an optical switch. Such switch includes a prism. The prism has input and output surfaces. A reflecting surface connects ends of the input and output surfaces.
A substantially-planar base platform having a longitudinal axis supports the prism. A pivot member is arranged beneath the base platform and transverse to the axis of the platform so that the platform is rotatable about the member in the plane of the longitudinal axis.
Apparatus responsive to an input signal is arranged to cause the platform to be selectively rotated about the pivot member.
In a second aspect, the invention provides apparatus for selectively routing at least one input beam to a plurality of predetermined destinations. Such apparatus includes a plurality of prisms. Each prism defines a triangle in a horizontal plane with orthogonal input and output surfaces and a reflecting surface connecting each of the input and output surfaces.
A plurality of substantially-planar base platforms is provided. Each platform has a longitudinal axis and supports a prism.
A pivot member is arranged beneath each base platform and transverse to the axis of the associated platform so that the platform is rotatable about the member in the plane of the longitudinal axis.
Apparatus responsive to an input electrical signal is arranged to cause each platform to be selectively rotated about the associated member. A controller is provided for selectively energizing such apparatus whereby the attitudes of the platforms are responsive to the controller.
In a third aspect, the invention provides an optical switch. Such switch includes a reflective surface. A substantially-planar base platform having a longitudinal axis supports the reflective surface.
A pivot member is arranged beneath the base platform and transverse to the axis of the platform so that the platform is rotatable about the member in the plane of the longitudinal axis. Apparatus responsive to an input signal is arranged to cause the platform to be selectively rotated about the pivot member.
The foregoing and additional features of the invention will become further apparent from the detailed description that follows. Such description is accompanied by a set of drawing figures in which numerals, corresponding to those of the written description, point to the features of the invention. Like numerals refer to like features throughout both the written description and the drawing figures.